Int. J. Dev. Biol. In Press
doi: 10.1387/ijdb.160232nb
© UPV/EHU Press

Uncovering floor plate descendants in the ependyma of adult mouse CNS using mapping of Nato3-expressing cells

Sophie Khazanov, Yael Paz, Amit Hefetz, Ben Jerry Gonzales, Yaara Netser, Abed AlFatah Mansour*, and Nissim Ben-Arie*

Department of Cell and Developmental Biology, Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel

ABSTRACT During embryonic development of the central nervous system (CNS), the expression of the bHLH transcription factor Nato3 (Ferd3l) is unique and restricted to the floor plate of the neural tube. In mice lacking Nato3 the floor plate cells of the spinal cord do not fully maturate, whereas in the midbrain floor plate, progenitors lose some neurogenic activity, giving rise to a reduced population of dopaminergic neurons. Since the floor plate is considered to be disintegrated at the time of birth, Nato3 expression was never tested postnatally and in adult mice. Here, we utilized a Nato3 knockout mouse model in which a LacZ reporter precisely replaced the coding region under the endogenous regulatory elements, such as its expression recapitulates the spatiotemporal pattern of Nato3 expression. Nato3 was found to be expressed in the CNS throughout life in a highly restricted manner along the medial cavities: in subpopulations of cells in the IIIrd ventricle, the cerebral aqueduct, the IVth ventricle, the central canal of the spinal cord, and the subcommissural organ, a gland located in the midbrain. A few unifying themes are shared among all Nato3-positive cells: all are positioned in the midline, are of an ependymal type, and contact the cerebrospinal fluid (CSF) similarly to the embryonic position of the floor plate bordering the lumen of the neural tube. Taken together, Nato3 defines an unrecognized subpopulation of medial cells positioned at only one side of circular ependymal structures, and it may affect their regulatory activities and neuronal stem cell function.

Keywords:

Nato3, floor plate, ependyma, spinal cord, subcommissural organ

*Corresponding author e-mail: Nissim.Ben-Arie@mail.huji.ac.il ; Abed.Mansour@mail.huji.ac.il